Nicotinic acid adenine dinucleotide phosphate: A new Ca2+ releasing agent in kidney

Nicotinic acid adenine dinucleotide phosphate (NAADP), a molecule derived f rom beta -NADP, has been shown to trigger Ca2+ release from intracellular s tores of invertebrate eggs and mammalian cell microsomes. NAADP-induced Ca2 + release occurs through a mechanism distinct from that of inositol-1,4,5-t risphosphate- or cyclic ADP-ribose-elicited Ca2+ release. This study invest igated whether NAADP can be synthesized in rat kidney. Extracts from glomer uli, mesangial cells, and papilla have high NAADP synthetic capacities. Con versely, synthesis of NAADP in kidney cortex was almost undetectable. Furth ermore, 9-cis-retinoic acid significantly upregulated NAADP synthesis in me sangial cells. Authenticity of NAADP biosynthesis in glomeruli was affirmed by HPLC analysis. NAADP stimulated Ca2+ release from mesangial cell micros omes through a pathway distinct from that of inositol-1,4,5-trisphosphate o r cyclic ADP-ribose. NAADP-triggered Ca2+ release may play an important rol e in regulation of renal function.